1. Technical Field
The present disclosure relates to look-up tables, and specifically to a storage method for gamma value look-up tables.
2. Description of Related Art
A liquid crystal display (LCD) provides portability, low power consumption, and low radiation, and finds wide use in various portable information devices such as notebooks, personal digital assistants (PDAs), video cameras and others.
Gamma correction technology is widely used to improve the display quality of LCDs. A typical gamma correction technology requires gamma value look-up tables.
FIG. 2 shows a commonly used gamma value look-up table. Each gamma value is stored in a 10 bit form. The lower 8 bits from bit0(1) to bit7(1) of a gamma value corresponding to a 1st gray are stored in bit0 to bit7 of a byte corresponding to an address which is 0. The higher 2 bits from bit8(1) to bit9(1) are respectively stored in bit0 to bit1 of a byte corresponding to an address which is 4.
The lower 8 bits from bit0(2) to bit7(2) of a gamma value corresponding to a 2nd gray are stored in bit0 to bit7 of a byte corresponding to an address which is 1. The higher 2 bits from bit8(2) to bit9(2) are respectively stored in a bit2 to bit3 of a byte corresponding to an address which is 4.
The lower 8 bits from bit0(3) to bit7(3) of a gamma value corresponding to a 3rd gray are stored in bit0 to bit7 of a byte corresponding to an address which is 2. The higher 2 bits from bit8 (3) to bit9 (3) are respectively stored in a bit4 to bit5 of a byte corresponding to an address which is 4.
The lower 8 bits from bit0(4) to bit7(4) of a gamma value corresponding to a 4th gray are stored in bit0 to bit7 of a byte corresponding to an address which is 3. The higher 2 bits from bit8(4) to bit9(4) are respectively stored in a bit6 to bit7 of a byte corresponding to an address which is 4.
In sum, the gamma values corresponding to the 1st gray, the 2nd gray, the 3rd gray and the 4th gray are stored in the byte corresponding to the addresses from 0 to 4. In other words, four gamma values require 5 bytes of storage space. Correspondingly, 256 gamma values require 320 bytes of storage space. The gamma value look-up table requires 320 bytes of storage space. A color LCD includes three look-up tables for gamma values corresponding to red, green, and blue. For this reason, the three gamma value look-up tables require 960 bytes of storage space.
It is preferred to store the three gamma value look-up tables, along with an On-Screen Display (OSD) application supporting parameters relating to brightness, contrast, borders, and color temperature of the display, in 1024 bytes of memory. Because a typical OSD parameter needs 180 bytes of storage space, 844 bytes of storage space remain in the memory, insufficient in this case to accommodate the three gamma value look-up tables.
What is thus called for is a storage method for gamma value look-up tables which can overcome the above-described deficiencies.